System and method for slip sheet evacuation

ABSTRACT

A system and method for slip sheet disposal from a plate imaging device or printing device comprises a slip sheet dispensing means configured for dispensing the slip sheets from the plate imaging device and an air release module configured to apply air flow between the slip sheets and the slip sheet sliding tray during the slip sheets dispensing from the plate imaging device or printing device.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly-assigned co-pending U.S. patentapplication Ser. No. 12/045,061, filed Mar. 10, 2008, entitled: “PlatePallet Stock Detection”, by Korolik et al., the disclosure of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a plate imaging devices, and moreparticularly, to systems configured to properly evacuate separated slipsheets from plate imaging devices.

BACKGROUND OF THE INVENTION

Prior to setting forth the background of the invention in detail, it maybe helpful to set forth definitions of certain terms that will be usedhereinafter.

The term “Computer to plate” (hereinafter: CTP) as used herein in thisapplication, relates to an imaging technology used in modern printingprocesses. In this technology, an image created in a Desktop Publishingapplication is output directly to a printing plate. CTP as usedhereinafter relates also to the imaging device carrying the process ofoutputting the computer-stored image on the printing plates.

The term “Printing Plates” (sometimes referred to as “plate” or“plates”) as used herein in this application, relates to the flexiblealuminum or plastic precursor printing plate elements that are imagedand developed to form lithographic printing plates that are then used inoff-set printing technology. Traditional printing plates have a brushedor roughened texture and are covered with a photosensitive emulsion. Aphotographic negative of the desired image is placed in contact with theemulsion and the plate is exposed to light. After development, theemulsion shows a reverse of the negative image, which is thus aduplicate of the original (positive) image. The image on the plateemulsion can also be created through direct laser imaging in a CTPimaging device. Printing plates are typically stacked in a cassette, ona pallet or similar container which houses the plates and facilitatestheir protection, transportation, and handling, before loading them intoa dedicated tray within a CTP imaging device.

The term “Slip Sheet” (hereinafter: “slip sheet”) as used herein in thisapplication, relates to interleaves, usually in the form of paper sheetsthat are packed between the printing plates and are used to separate theplates. Slip sheets are also known in the industry as: “separationpapers”, “slip sheets”, “slip papers”, or “leaf sheets”.

Every CTP imaging device usually comprises trays for accommodating theprinting plates exhibiting specific dimensions. Trays can usually bearranged to contain plates of various sizes, but all plates in the sametray are of one size. The plates may be manually removed from thecassette, pallet or a shipping container and then inserted into thetrays for use by the CTP imaging device.

After the plates are loaded into a CTP imaging device tray and prior tothe plate loading, the slip sheet is removed from the loaded plate.According to the traditional art, the slip sheet is removed from the CTPdevice using a slip sheet disposal system. Such a traditional system isillustrated in FIG. 1 that shows a side view of a system for disposingof slip sheets in a CTP imaging device according to the prior art inwhich slip sheet 14 is brought into disposal system 10. Slip sheet 14 isclamped using a slip sheet clamp 11 to a roller 12. Roller 12 radialmovement evacuates slip sheet 14 outside system 10 towards direction 15.

Due to the currently available structure, slip sheet 14 may be chargedwith static electricity, accumulated during plate packaging or plateshipment. In this case slip sheet 14 may be undesirably attached to thesliding tray 13 thus blocking the evacuation path of imminent slipsheets.

Therefore, there is a recognized need for a slip sheet disposal systemequipped with means to avoid accumulated static electricity.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided asystem for facilitating slip sheets disposal using air flow, the systembeing operatively associated with a plate stack comprising platesseparated by slip sheets, the system comprising: a slip sheet dispensingmeans; a slip sheet sliding tray operatively associated with the a slipsheet dispensing means; an air release module operatively associatedwith the slip sheet sliding tray, wherein the slip sheet dispensingmeans is arranged to dispense a slip sheet from the plate track andslide it on top of the slip sheet sliding tray; and wherein the airrelease module is arranged to output air flow between the top of theslip sheet sliding tray and the slip sheet thus facilitating the slidingof the slip sheet over the slip sheet sliding tray.

This invention also provides a method of facilitation sliding of a slipsheet from a plate stack over a tray within an imaging device, themethod

-   -   comprising: dispensing a slip sheet from a plate stack;    -   sliding the slip sheet over the tray; and    -   outputting air flow between the slip sheet and the tray.

These and other objects, features, and advantages of the presentinvention will become apparent to those skilled in the art upon areading of the following detailed description when taken in conjunctionwith the drawings wherein there is shown and described an illustrativeembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention will become more clearlyunderstood in light of the ensuing description of embodiments herein,given by way of example and for purposes of illustrative discussion ofthe present invention only, with reference to the accompanying drawings(Figures, or simply “FIG.”), wherein:

FIG. 1 is schematic illustration of a slip sheet disposal systemaccording to the prior art;

FIG. 2 is a is a schematic illustration of a CTP imaging device thatcomprises the system according to some embodiments of the presentinvention;

FIG. 3 is schematic illustration of a slip sheet disposal systemequipped with air jets according to some embodiments of the presentinvention;

FIG. 4 is schematic illustration of a slip sheet disposal systemequipped with an evacuation path exhibiting air flow opening accordingto some embodiments of the present invention; and

FIG. 5 is a high level flow chart showing a method according to someembodiments of the present invention.

The drawings together with the description make apparent to thoseskilled in the art how the invention may be embodied in practice.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the disclosure.However, it will be understood by those skilled in the art that theteachings of the present disclosure may be practiced without thesespecific details. In other instances, well-known methods, procedures,components and circuits have not been described in detail so as not toobscure the teachings of the present disclosure.

The present invention describes a slip sheet removal system integratedin a CTP imaging device. The invention enables smooth slip sheetsremoval from the imaging device, avoiding jams in the slip sheet removalpath, typically created due to accumulated static electricity and tofriction between slip sheet and slide element.

FIG. 2 shows a schematic view of a CTP imaging device 20 configured withan automatic plate loader in accordance with embodiments of the presentinvention. Plate stack 21 is shown inside CTP imaging device 20. Eachplate in plate stack 21 comprises a metal based plate separated by slipsheet 14 (not shown). Slip sheet 14 is separated from the plate beforeimaging. Separated slip sheet 14 is removed from imaging device 20 by aslip sheet disposal system (not shown) with air release means (notshown). The disposal system is integrated inside imaging device 20.

FIG. 3 shows a schematic side view of a slip sheet disposal system 30according to some embodiments of the invention. Sheet disposal system 30comprises a slip sheet clamp 11 operatively associated with a platestack (not shown), a roller 12, on which slip sheet clamp 11 is abutted,and a sliding slip sheet tray 13 located in proximity to roller 12 suchthat slip sheet 14 may be easily transferred from roller 12 to slidingslip sheet tray 13. Slip sheet disposal system 30 further comprises anair release module that may comprise a compression module 33 coupled toa conduit 31 located and arranged to output an air flow between slidingslip sheet tray 13 and slip sheet 14.

In operation, roller 12, by rotating on the plate stack 21, lifts thetop slip sheet 14 off the plate stack 21 and forces it in between clamp11 and roller 12. Roller 12 continues to rotate causing the transfer ofslip sheet 14 to the top side of sliding slip sheet tray 13. Then, aircompression module 33 is arranged to output an air flow 32 via conduit31 to the space defined by the top surface of sliding slip sheet tray 13and slip sheet 14. Air flow 32 electrically insulates slip sheet 14 fromsliding slip sheet tray 13 thus preventing any static electricity basedor friction based attachment of slip sheet 14 to sliding slip sheet tray13 which may result in slip sheet jamming.

According to some embodiments of the invention. Air flow 32 is appliedin synchronization with the removal of slip sheet 14 by roller 12.Specifically, the synchronized action of rolling roller 12 and aircompression module 33 is arranged to create an air cushion 35 betweenslip sheet 14 and sliding slip sheet tray 13. As explained above aircushion 35 prevents any contact between slip sheet 14 and sliding slipsheet tray 13 throughout the removal process of slip sheet 14. Thus, aircushion 35 enables smooth removal of slip sheet 14 from imaging device20.

According to some embodiments of the invention, the air compressionmodule may be internal and contained within the imaging device oralternatively, the compressed air may be supplied from an externalsource.

According to some embodiments of the invention, conduit 31 is locatedand shaped such that air flow is outputted as an air jet in thedirection of the sliding of the slip sheet.

According to some embodiments of the invention, the air dispersion meansfurther comprises an air nozzle so that the air flow may be optimallyshaped to facilitate the separation of slip sheet 14 from slip sheetsliding tray 13.

According to some embodiments of the invention, the air dispersion meansfurther comprises another conduit which is narrower than the firstconduit. This enables further control over the flow of the air and maybe arranged to output a high speed flow capable of easy separation ofslip sheet 14 and slip sheet sliding tray 13.

According to some embodiments of the invention, the narrower conduit asexplained above exhibits an aperture of an ellipsoidal shape.

According to some embodiments of the invention top surface of the slipsheet sliding tray may be a straight surface, a curved surface or anycombination thereof.

FIG. 4 shows a schematic top view of the slip sheet disposal systemaccording to some embodiments of the invention. Sheet disposal system 30comprises slip sheet dispenser 11, roller 12 and slip sheet sliding tray13 as detailed above. Slip sheet sliding tray 13 comprises a pluralityof opening 40 located throughout its surface. Air compression module(not shown) is arranged to output air flow through plurality of openings40 wile roller 12 slides slip sheet 14 over slip sheet sliding tray 13.The air flow from openings 40 flow in a perpendicular direction to thedirection of sliding of slip sheet 14. This arrangement maximizes thatimpact of the air flow in separating slip sheet 14 from slip sheetsliding tray 13.

Advantageously, the aforementioned slip sheet disposal system isincorporated within an imaging device and preferably, a CTP imagingdevice. However, it is understood that the disclosed system may beeasily fitted into other devices requiring the quick and easy disposalof slip sheets from a stack of elements that are separated by slipsheets.

FIG. 5 shows a high level flow chart showing the steps in a method offacilitation the sliding of a slip sheet from a plate stack over a traywithin an imaging device, according to some embodiments of the presentinvention. The method comprising: dispensing a slip sheet from a platestack 51; sliding the slip sheet over the tray 52; and outputting airflow between the slip sheet and the tray 53.

According to some embodiments of the invention, sliding the slip sheetover the tray and outputting air flow between the slip sheet and thetray occur in synchronization as so to optimize the impact of the airflow on facilitation of the separation of slip sheet 14 from slip sheetsliding tray 13.

According to some embodiments of the invention, outputting of air flowbetween the slip sheet and the tray may be in the direction parallel tothe sliding direction thus applying thrust on slip sheet 14 in theadvancement direction of the sliding.

According to some embodiments of the invention, outputting of air flowbetween the slip sheet and the tray may be in the directionperpendicular to the sliding direction of the slip sheet. This willmaximize the impact of the air flow in separating slip sheet 14 fromslip sheet sliding tray 13.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention.

While the invention has been described with respect to a limited numberof embodiments, these should not be construed as limitations on thescope of the invention, but rather as exemplifications of some of thepreferred embodiments. Other possible variations, modifications, andapplications are also within the scope of the invention. Accordingly,the scope of the invention should not be limited by what has thus farbeen described, but by the appended claims and their legal equivalents.

Parts List

-   10—slip sheet disposal system—prior art-   11—slip sheet clamp-   12—roller-   13—sliding slip sheet tray-   14—slip sheet-   15—slip sheet movement direction-   20—CTP imaging device configured with an automatic plate loader-   21—Plate stack-   30—slip sheet disposal system with air jet-   31—conduit-   32—air between slip sheet and slip sheet tray-   33—air compression module-   35—air cushion-   40—air flow openings

1. A system for facilitating slip sheets disposal using air flow, thesystem being operatively associated with a plate stack comprising platesseparated by slip sheets, the system comprising: a slip sheet clamp anda roller arranged in cooperation to pull a slip sheet from the platestack and slide it on top of a slip sheet sliding tray; an air releasemodule operatively associated with the slip sheet sliding tray, whereina slip sheet dispensing means is arranged to dispense the slip sheetfrom the plate stack and slide it on top of the slip sheet sliding tray;and wherein the air release module is arranged to output air flowbetween the top of the slip sheet sliding tray and the slip sheet thusfacilitating the sliding of the slip sheet over the slip sheet slidingtray.
 2. (canceled)
 3. The system according to claim 1, wherein the airrelease module comprises an air compression module coupled to an airdispensing means.
 4. The system according to claim 3, wherein the aircompression module is internal.
 5. The system according to claim 3,wherein the air compression module is external.
 6. The system accordingto claim 3, wherein the air dispensing means is a conduit located andshaped such that air flow is outputted as an air jet in the direction ofthe sliding of the slip sheet.
 7. The system according to claim 6,wherein the air dispersion means further comprises an air nozzle.
 8. Thesystem according to claim 6, wherein the conduit end as narrower thanthe conduit.
 9. The system according to claim 8, wherein the conduit endexhibits an aperture of an ellipsoidal shape.
 10. The system accordingto claim 3, wherein the air dispersion means comprises a plurality ofopenings located on the top surface of the slip sheet sliding tray andwherein the air compression module is arranged to output an air flowthrough the plurality of openings.
 11. The system according to claim 1,wherein the top surface of the slip sheet sliding tray is a straightsurface.
 12. The system according to claim 1, wherein the top surface ofthe slip sheet sliding tray is a curved surface.
 13. The systemaccording to claim 1 wherein the top surface of the slip sheet slidingtray is a combination of a straight and a curved surface.
 14. The systemaccording to claim 1, wherein the system is incorporated within animaging device.
 15. The systems according to claim 1, wherein the systemis incorporated within a computer-to-plate imaging device.
 16. A methodof facilitation sliding of a slip sheet from a plate stack over a traywithin an imaging device, the method comprising: dispensing a slip sheetfrom a plate stack; sliding the slip sheet over the tray; and outputtingair flow between the slip sheet and the tray.
 17. (canceled)
 18. Themethod of claim 16, wherein outputting of air flow between the slipsheet and the tray is in the direction parallel to the sliding directionof the slip sheet.
 19. The method of claim 16, wherein outputting of airflow between the slip sheet and the tray is in the directionperpendicular to the sliding direction of the slip sheet.